This invention relates to a shoe bolt securing and removing apparatus for connecting and disconnecting between track links and track shoes in the track chain of a track type vehicle.
Hithertofore, in order to secure or remove shoe bolts which fixedly connect between track links and track shoes in a track chain of a track type vehicle, when the chain is newly assembled or repaired or serviced, the usual way has been to lay the chain 1 flat so that the track shoes 4 rest on track links 2 (for assembling a new chain 1) or the chain 1 is placed on a conveyor in an extended condition (for repairing or servicing the chain) as shown in FIG. 1, the nut wrench 6 (as shown in FIG. 2) is inserted into the opening in one of the series of track links 2 to engage one of nuts 8 positioned below the associated track shoe 4 so as to hold the one nut against turning and the shoe bolt wrench delivers an impact rotation to the bolt head of associated shoe bolt 10 so as to turn the bolt for securing the bolt to or removing the bolt from the track chain 1. The same procedure is repeated for the other shoe bolts 10 to complete the assembly or disassembly of the track chain.
One example of the type of shoe bolt wrench generally useful for the above-mentioned purpose is illustrated in FIG. 3. The shoe bolt wrench includes a carriage 12 slidably movable along a conveyor and an elongated frame 14 supported in the center 14' in the longitudinal direction thereof on the carriage 12. The height of the frame 14 with respect to the carriage 12 is adjustable by the use of a jack 16 and the frame is rockable about the center 14' in horizontal and vertical planes. The frame 14 has an impact wrench 18 mounted at one end for fastening or loosening a shoe bolt and an electric motor 20 mounted at the other end for concurrently driving the impact wrench 18 and serving as a counter weight to balance the frame 14. In order to deliver an impact to the head of a shoe bolt to turn the bolt by the use of the shoe bolt wrench, each time one shoe bolt is secured to or removed from the track chain, the carriage 12 is moved along the conveyor to a suitable position for the operation and the handle 22 mounted on the frame 14 is turned to rock the frame 14 until the socket of the impact wrench 18 fits on the head of the shoe bolt. In addition to the above-mentioned type shoe bolt wrench, hydraulic and pneumatic shoe bolt wrenches are known in which hydraulic or air pressure is employed as drive means for the impact wrench 18 in place of the electric motor 20 as provided in the above-mentioned motor driven type shoe bolt wrench. In addition to the difference with respect to drive means, the hydraulic or pneumatic shoe bolt wrench differs from the motor-driven shoe bolt wrench in the fact that a counter weight is mounted on the frame 14 in the position where the electric motor 20 would be positioned in the motor driven type shoe bolt wrench and the hydraulic and pneumatic shoe bolt wrenches are similar to the motor driven shoe bolt wrench with respect to other components.
However, in any one of the above-mentioned shoe bolt securing and removing apparatuses, each time one shoe bolt is secured or removed, the shoe bolt wrench and carriage assembly having a substantially heavy weight is moved along a conveyor with the portion of the frame 14 where the impact wrench is mounted being manually upheld and the handle 22 is turned to bodily rock the frame 14 until the socket of the impact wrench 18 comes into alignment with the head of the shoe bolt 8 whereas with respect to the nut, the nut wrench 6 is inserted in the opening in the track link 2 so as to engage the socket thereof on the nut on the shoe bolt shank positioned below the track shoe 4. The nut wrench 18 is required to be manually held in position during the turning of the impact wrench 18. Thus, the shoe bolt securing and removing operation requires two operators one of whom is assigned for the bolt handling with the other assigned for the nut handling and thus, the alignment of the impact wrench 18 with the bolt 10 and that of the nut wrench 6 with the nut 8 are separately carried out which reduces the operation efficiency. Also, the movement of the carriage 12 and the rocking of the frame 14 which are necessary in order to align the socket of the impact wrench 18 with a particular shoe bolt 10, are manually performed. In addition, since the nut wrench 6 is required to be manually held in position as the shoe bolt is turned by the impact wrench 18, the operators are soon physically fatigued, particularly, since the body of the operator is subjected to vibration due to impact generated during the turning of the bolt by the impact wrench 18. Therefore, securing and removing shoe bolts by the use of the conventional shoe bolt securing and removing devices is undesirable from the view point of workers' health. Furthermore, since the impact wrench 18 is designed to rock about the central portion 14' of the frame 14 in the longitudinaI direction thereof describing a circle, there is the disadvantage that the socket at the leading end of the impact wrench 18 does not always precisely fit on the bolt head.